I’ve been dipping into Michael Erard’s book, Um. Yes, that’s the title. The subtitle is Slips, Stumbles, and Verbal Blunders, and What They Mean. Chances are you won’t be surprised to know that in American English, um and uh are the most common blunders, or fillers, accounting for 40 percent of what Erard calls “speech disturbances.” Those are words that interrupt the smooth flow of sentences.
In other places, people have their own fillers: in Britain, they say uh but spell it er (think of a Brit saying water or butter—you won’t hear an R at the end of those words). French speakers say something close to euh. Germans say äh and ähm, Hebrew speakers use ehhh, and Swedes say eh, ah, aaah, m, mm, hmm, ooh, a, and oh. Very versatile.
The point is that around the world, linguistic blunders exist, no matter the language. However, if you want to be a citizen of the world, um is pretty much universal.