I have read on several issues like this in the fccuk forum. It seems to be like coupe99999 suggests. A bit of corrosion. Which makes the resistance higher. Thus leading to heat.
Changing a fuel pump is doable, I did mine though combining with a revision of the rear axle so the fuel tank was removed. You can change the pump via the rear trunk though. For the 20vt new pumps are available on sites like autodoc, you can try for your 1.8. They are not expensive, though a change is probably not needed in your case.