Overwhelmed with choices

I have a Century Motor/Pump combination which i think is desgnated WFE-4.  Motor shot.  I was hoping to go with a energy efficient variable speed combo, but, do not want the hassle of replumbing.  Is there somthing I can just drop in the same location without major replumbing ?  The pump housing is old and looks worn, so, i am guessing  I cannot just replace the motor.  Thanks for any advice.  Mark