My juwel pumps knackered...

[lucysmam]

is it worth taking the impeller & other removeable bits off it as spares for the new one I'm waiting for?

Yes, always worth having spares. What happened to it? How long has it been off? Your tank might go through the cycle again so it might also be a good idea to arm yourself with a bottle of ammolock or some bactinettes unless you've got a spare mature filter.

sponges from the internal are already in the spare no need to panic

Ah, that's good news then! :)