According to :
"By the way, if your well pump is very old, you may want to consider
replacing it anyway. Newer motors run on much less power than ones
built just 10 years ago. "

You'd have to pump a hell of a lot of water for any difference in pump
efficiency to make up the cost of a new submersible pump, including
installation.

Neither electric motors nor the laws of physics have changed much in the
past few decades. At most, it could be a few percentage points
more efficient. Absolutely NO reason to replace a decent working
pump on that basis.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.