Product review (5 stars): Whirlpool Duet Washer GHW9150PW0
Perfect fit for the washer.  As other reviewers noted, this is the pump only.  Three screws on the pump housing - very easy to replace; keep the o-ring gasket from the old pump as this does not come with it.  There are online videos showing how to get at the pump.  I never worked on any appliance previously and was able to replace the pump with no issues.  If your washer isn't on a pedestal, draining the remaining water (after bailing out the washer drum) could be a little messy - have some towels handy.