I'm no mechanic, but back in the days when space in the engine compartment was much less efficiently used I could do some repairs/replacements myself. When the water pump on my old-style Skoda (butt of many a joke) failed I went to the nearest scrapyard and got a replacement for £5. Took about ten minutes to swap over, though I noticed the vanes on the replacements were about half the depth of those on the original, but it fit and seemed to work. Later, when looking up something else in the workshop manual I found it said the water pump changed in this respect in a certain year and "on no account" should one be replaced by the other. By this time I had been driving with it for over a year without mishap!