K Y Jelly

KY Jelly and/or glycerine (AKA glycerol) will be perfectly OK to use on the impeller.
Silicone grease will work nicely too.
Vaseline will work but risks perishing certain types of rubber impeller.
Fairy liquid does not contain strong oxidants and can be used to lubricate the impeller.

If the impeller is difficult to reinstall, try tightening cable ties round the blades to hold them flat, then snip each tie off as it reaches the pump housing.
 
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