According to Tony :
One thing i've noticed over time in rebuilding these pumps is that grit and
metal filings seemed to get embedded in the composite plastic vanes
(probably debris that got passed the strainer) and scores the pump
housings.

I was leaning towards aluminum vanes since I think they are less likely to
do damage to the cast iron housing. Brass or bronze might be even
better/longer lasting.

Note that when lapping, the harder material is what is cut,
because the abrasive embeds in the softer material. So based on that,
you would want steel for the vanes.

But something like graphite which does not tend to accept things
embedding in it, but which wears to conform to the contour of the
housing would perhaps be the best choice.

Good Luck,
DoN.
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