I guess ur friend has a full insurance.

Here is how it works.
1) he needs to pay a deductible amount - Its around QR 500 nromally but it differs for companies and type of cars etc. it would be mentioned in the insurance copy.
2) he doesnt need to pay anything for the repair / replacement of the parts if he agrees for old / duplicate parts (unless his car is less than 1 year old).
3) if he insists on genuine / new parts, he has to pay from his pocket.

hope that makes it clear.