Hotpoint HBC2819XUKN circulation motor failure

Purchased a Hotpoint HBC2819XUKN in March, and used it maybe 15 times.
We left the house for 5 months, and on our return the dishwater would fill, but the circulation pump would not start (could hear a very quiet hum)
The pump has now been swapped out under warranty and works as expected.
I had a look at the old pump and the rotor can be pulled out, and the shaft of the rotor has rusted

So I guess that the rust provided enough resistance to indicate a fault condition and prevented the motor from starting.
I just wondered if anyone else has come across this, and if there is any advice to prevent this from happening again.