Closest we will ever see is this:
https://www.antiquegamblingchips.com/mfgchip.htm
Short of
CPC or Paulson letting us see what happens inside (basically never going to happen because of gaming commission rules and trade secrets) this is the best we have.
Short answer, inlay is pressed into the clay of the chip as part of the process. Maybe a tiny dab of glue to hold it in place as part of the process, but the inlay becomes part of the chip as part of the process and not just stuck on.