I am not entirely happy w/ metal impeller w/p: the car runs slightly hotter.
Hmm...that's the reason I replaced my plastic one in the first place. I'd been reading about the failed pumps on here for months and the temp started moving to the right half of NORMAL. Since it had over 70,000 miles I figured it was time to replace it when it was convenient for me, not after waiting for the thing to disintegrate.
My metal impeller pump keeps the gauge between the O and the R most of the time.
Did you install a new thermostat and flush out the system while you had the pump off?