You have provided a very good description of the fungus gnat larvae that live on decaying organic matter (roots, bark chips, compost) in the potting soil. Yes, the larvae
can be seen if you look carefully as you did. In time they will mature into adults with wings and you will have gnats flying about. Sometimes the gnats lay more eggs in the soil of other
plants.
It is important to treat the problem now before the adults emerge and the problem
spreads. Here's how:
Scrape off as much of the top layer of soil as you can without damaging the roots. Allow the soil to become as dry as possible without killing the
plant.
Add a thin layer of sharp sand or diatomaceous earth to cover the surface of the soil. These substances will physically carve up the larvae as they move toward the surface.
Another method is to place a half inch slice of raw
potato on the surface of the soil. The larvae will go to the
potato. Remove and replace the
potato slice periodically. Eventually you will have removed all of the larvae.