It's a bad argument to have with a christian, because the implication is "the Bible gets math wrong, so it's wrong", and then the christian gets to say "no, you're misreading it. The math is right, so the Bible is right". Obviously that's a fallacious conclusion, but it's an easy one to make, and why set them up for shooting down your point?
Pi works out fine if you assume there's a lip of a particular size on the vessel being described, that they walked around it to get the circumference, and measured across the inside for the diameter, and you don't derive pi because you're dealing with two different circles.
The easiest explanation for Ezra is that it isn't an exhaustive list. I have 3 dress shirts and 5 short sleeve shorts and all my shirts number 18. It looks wrong because they use 'vessel' twice, but now we have to argue about what those phrases meant exactly in ancient greek or hebrew, and they can always fall back on there being small corruptions of old testament text over thousands of years, but that the basic truths were preserved.
As great as it would be for the Bible to have blatant mathematical errors, it seems more likely that the text changed slightly with all the retellings and copyings than that nobody could figure out what 1,000 + 1,000 added up to.
All that said, what is up with the objection to infinite sets? It's funny how small some people's Gods are, that they can't be infinite or coexist with the idea of infinity, that Earth must be the center, because God couldn't possibly have made multiple worlds, that there's no way God could be as subtle as to use evolution...