I found these new water pumps on British Parts of Utah, check them out, $140, 2 year warranty and look at that impeller, it appears to be bronze and real heavy duty.

 

Bronze is certainly preferred over steel as an impeller in many other types of pumps. This pix shows what an old D1 (175K) looked like. The curved cast bronze should have better flow performance than the simple stamped metal OEM impeller.

 

damn I just replaced mine 2 weeks ago...