How can I ensure that my new injector pump won't be destroyed by the swarf ?

My Renault Kangoo van broke down. Called RAC. The man came out and told me that my injector pump was breaking up. Booked it into a garage. When I went back to collect it a week later he had got the injectors reconditioned and he said the pump was OK. Got about twenty miles when the symptoms started again. Took it to another garage and it turned out that the injector pump was banjaxed and the swarf had buggered up the injectors which meant I had to get them reconditioned again. Now I've been told that it is likely that the pump will soon go again because it is impossible to get all the filings out of the system.
Is there anything I can do to ensure that this doesn't happen? I heard once about a magnet that can be placed around the filter which holds any metal particles in the filter, but I'm not sure if these filings are magnetic. I'm very worried about this as it has already cost me almost £2000 and I don't want it to happen again. Is this problem particularly prevalent in Renaults. If so what make would you advise me to go for?