I just heard ‘zumba’ mispronounced by my in-car speach-to-text: around here it’s pronounced “zoomba” Which got me wondering:
What English words do you know that use u for oo sound?
Is it more common in Brazil/Portugal/Latin countries?
I don’t do spelling. For me, this is difficult.
Not more common, it is how we spell the /u/ sound in Spanish, Portuguese, Italian, Catalan, Galego, Basque… Booboo Bear is called Bubú (with or without the little mark depending on language).
“Portuguese” 
Now I’m wondering if there is any English dialect which turns that single vowel into a diphthong…
The Great Vowel Shift made all the English vowels diverge from Continental European languages. — Great Vowel Shift - Wikipedia
That’s why in IPA, the symbols [a e i o u] represent the simple spelling of Italian, Spanish, and German, for example, have to be learned by Anglo monoglots and it’s why in English the letter names have to be transcribed [eɪ i aɪ əʊ/oʊ ju]
Round here Zumba is pronounced with the ‘u’ sound somewhere between the long and the short sound.
Plenty of English words with a long ‘u’ sound, but they usually have an ‘e’ at the end, like ‘rude’ or ‘amuse’
To clarify: How was it mispronounced?
Is this thread about the difference between “oo” and “uh,” or about the difference between “oo” and “yoo”?
Not quite the same, but it took me years of seeing this comic pop up in random places (both my brother and I liked the Far Side, so there were some books and calenders around the house) before I understood it.
In most languages I know or am familiar with, the “u” represents an “oo” sound, assuming you mean “too” as in “too” and not “oo” as in “book.” I would say it’s represented as /u/ in IPA, but, obviously, that doesn’t help in this case. 
So, in addition to the languages above, it’s also true for Polish (and other Slavic languages) and Hungarian as well. French makes a sound like the German ü, so not quite the same as an “oo.”
“Long” and “short” don’t really translate across accents.
Is the question whether Zumba goes like number, Roomba, or wool?
[ˈnʌm bɚ] [ˈzʌm bə]
[ˈɹum bə] [ˈzum bə]
[wʊl] [ˈzʊm bə]
Those are two different vowels
[rud] [ə ˈmjuz]
Nuclear.
I hear njuclear all the time. I suspect English does not really play well with pure vowels.
Super
Stupid
Tumor
Puma
[ju:] versus [u:] is a dialect thing so YMMV.
Naw, it’s njucyyou-lar 
I wonder if the OP was wondering “zumba” pronounced to rhyme with “dumb-ba” versus the “oo” in “room” vs the “oo” in “book”.
Also the “u” as a long vowel is extremely common in English. That rhymes with oo as in room. Using it to rhyme with book isn’t unheard of either - e.g. “put”, though not quite as common.
I’m not sure I understand the question. Pronouncing English u as ‘oo’ (IPA /uː/) is not at all rare. A u followed by a e later in the same syllable is very often (possibly in most cases) pronounced ‘oo.’ Hence blue, chute, true, include, etc. Even without the e, the ‘oo’ pronunciation is very common, with hundreds, maybe thousands, of examples. Some of them have sort of an implied e later in the same syllable (E.g., dilution from dilute, but many do not)
absolution
beluga
cerulean
dilution
effluvium
fluid
glucose
hallelujah
intuition
jubilation
kudos
lubrication
marsupial
numeral
occlusion
plumage
quadruped
rhubarb
super
tuna
unruly (second u)
vicuna
zucchini
I admit I couldn’t find any examples starting with w, x, or y.
Watusi
Xanthinuria
Yule
Ok maybe the first two aren’t really English words.
Watusi was also a dance craze.
Neither is Zumba. Spanish for “it buzzes” or “[imperative] buzz”.
Nm
Huh nobody’s mentioned the first word that came to my mind.
Tuba.
/rud/ is a different vowel from /əˈmjuz/?
Well, yes, in English we distinguish between /u/ and /ju/. I think most English speakers, when asked what the vowel in the second syllable of “amuse” is, would say “you,” not “oo.” So while “you” may be a diphthong and not a pure vowel, it is represented by the letter “u” in many words.
