That looks like a good condition playfield, there are a few option for the cupped inserts. i've seen posts where some are filled and leveled with a resin, others remove from the playfield and sand flat.
Maybe consider first trying a playfield protector, it may level over those inserts, provide protection, overal, and be reusable should you explore other options.
https://pinside.com/pinball/forum/topic/lexan-playfield-protector-install-and-review