Some light hints that may point you in the right direction:
Hint 1
The assembly is a part of a larger machine.
Hint 2
Several assemblies are meant to move side by side in unison.
Hint 3
The square-ish shaped piece is plastic that will wear down and be replaced.
Almost looks like the inside of a piano key
Edit: just read the hints and it kinda fits
Not for a piano. It’s more industrial.