I had the same thing in my soil, was really worried they would damage the plant but as far as i could see the roots were fine, but i didn't like them being there!
I managed to kill them all without using chemicals and with no damage to the plant. Basically i got one of those USB coffee mug heaters you can buy online, i got mine for about £3. i attached power wires to only the heating elements and also scratched off any green power rails which went to any other part of the device (because this was a USB hub also) so that the heating elements were the only things being powered. I hooked it up to a DC transformer outputting around 8V to make the heating plate a little hotter, i'd say it was around 60°C. i then generously watered my plant and placed it on this heating unit, i then covered the top of the plant pot with a plastic cup to keep the warmth contained , although the heating pad was hot the heat being transfered to the actual soil wasn't much, i'd say the soil temperature was 30-40°C. I kept it like this for about a week or two and when i checked on it all of the bugs in the soil were dead and there were a few crawling inside the cup (as it was cooler) and simply threw them away with the cup!
I did a cheeky check on the roots and they were doing absolutely fine, no damage at all. My plant was a seedling at this point with no leaves, so airflow was not an issue, which is why i could get away with using the cup ontop. if your plant has leaves or is too big to do this then maybe a chemical insecticide might be more appropriate, cause i think what made my technique work was that these bugs hate warmth and will die in warm environments, and with a cup ontop of the pot it meant that not only could they not escape but it was a hot environment wherever they went.