After changing a few water pumps and reading through the forums, I've become a
water pump heretic.
I see no reason to buy an expensive pump, and I see the metal vs composite impeller as a moot point. I will be changing mine about every two years and running Zerex or Prestone as my coolant. I do not trust an OEM pump much longer than that anyway. If I can get a Pierburg for about $150 sure, but otherwise GMB, Gates, Beck Arnley ~$100 and I'm satisfied for two years, then changing it again.
Not doing this:
and this:
again.
The task itself is pretty easy.
If I sell, I'm informing and explaining.