Thanks for the visuals. This helps a lot.
Before experimenting with different materials, try using any available material and avoid brass inserts. While brass is strong, it sacrifices plastic wall thickness. Instead, include a small hole in your model for direct tapping. The combined strength of thicker walls and the ability to make disposable components might make a plastic part more practical than a metal/plastic combo.
Once you’ve experimented with tapping the holes directly, you’ll have a better feel for how the product will perform. For me as an example, I do all my prototyping in PLA. Then I move up to PETG and for the most strongest I use PC. Truth be told, I have PLA parts using metal screws that were tapped just using the screw itself as a tap and the performance will surprise you.
I’m sure in your line of work you have ample access to taps, but this lazy man’s drill-tap combo that I purchased some time ago is this one from Amazon is my go-to tool of choice when making cutting threads directly into plastic. I keep it right by my other 3D printing tools. I have another one for Metric. What I like is the combo drill bit, which allows me to be lazy about dimensioning holes in CAD.