FYI - I replace my pump with one that had a metal impeller. After reading the above link, it was stated that it might not work due to spinning at almost the same RPM as the engine. I was more worried about the effect of dis-similer metals in the cooling system and the corrosion effect that may occur. It's been almost two years now with no adverse effects.
Just my two cents worth.
Good luck! Hope the engine is not fried.
