I don't think earthworms would normally feature in a scorpions diet. So, whether they would even bother with them if offered as food I don't know. I think you'd more than likely find that the worms would tunnel into the substrate and never be seen again. This isn't necessarily a bad thing though. If the scorpions you keep live in humid enclosures with a soil/peat substrate, worms will help remove any detritus etc. Planted/natural vivaria enthusiasts often use worms alongside woodlice, springtails, roaches etc. as part of a clean up crew.
You could have a go, but if you do, as mentioned above be careful where you collect them from. Either buy them from bait or reptile shops, or collect them from somewhere you know that pesticides etc. haven't been used. As an extra precaution you can quarantine them in some chemical free potting soil/compost for a couple of weeks to make sure any nasties they may have ingested have passed through the gut.
