Worcestershire sauce isn't pronounced the way it's spelled, and even experienced chefs sometimes have trouble saying it properly. It's understandable that you're still getting it wrong. Don't worry, though, Italian chef Pasquale Sciarappa is here to help: It's "won-cha-STEER sa-OOH-chay."
These are the outtakes from a stuffed mushroom demonstration on Sciarappa's YouTube channel, Orsara Recipes. He didn't go with the autentico Italian pronunciation in the final video, probably because his audience is so used to hearing it said the bogus English way. And what would the English know about Wonchasteer Saoochay? Niente.