Fiat have used the same drum brake wheel cylinder for donkey's years. The 1980s Uno had the same brakes and I suspect the parts go back way before that. The issue with all manufacturers is they don't bother themselves with corrosion. The issue with Fiats is the back brakes last too long so they are trashed with corrosion when its time to replace.
If the back plate is rusty - take it off de-rust, paint, etc.
Deeply grooved brake drums are worn out. But costs are low so replace the lot anyway. Rusty cylinder with flaking bolts is also well past it's use by date so change it out along with the brake pipe if necessary. Brake back plate ditto.