You should be able to find something very similar at a large auto parts store.
If not an auto parts store, check your phone directory for industrial supply or
ball bearing supply stores.
They may have an Italian or European product that's the same.
Look for a 2 part epoxy thread repair kit. Be sure the kit comes with a small tube of
"release agent" which you will need to get really strong new threads.
If not, you can go to a larger screw, but stick with the PT (Plastics Technology) thread form as it's alot stronger in engineering plastics like your footstrap inserts.
You might find an M7 or M8 PT screw somewhere.
Hope this helps,