Something is chewing on my pump electric cord?

[Meyer Jordan]

So I scratched harder to try to feel if the rubber comes off, then the white pattern came off like a thick layer of transparent skin/film.

That cross-hatch pattern is entirely too uniform to have been randomly made by any critter. The fact that you say that it peeled of only supports the idea that this film was an outer waterproof coating applied when the cord was manufactured. Apparently a defective product.

 

[MitchM]

It looks to me like the cord may have been exposed to a petroleum based product that has damaged the outer layer.

 

[HARO]

That cross-hatch pattern is entirely too uniform to have been randomly made by any critter. The fact that you say that it peeled of only supports the idea that this film was an outer waterproof coating applied when the cord was manufactured. Apparently a defective product.

I've seen similar 'damage' on electrical cords before, and I'd like to wager that the cord,if not the whole product, was made in China. They've been having problems with their plastics ever since the rest of the world forced them to stop using lead in the manufacturing process. This resulted in a brittle product that wears prematurely, often causing pumps and filters to fail.
John