Any chance of a good, focused, close-up? Have you looked at them with a simple hand lens to inspect the physical characteristics and movement? Aphids will usually move if you blow on them.

Also, a good look with a magnifying glass will allow you to look up pictures in order to compare for yourself.

Looks like whitefly pupae just from what we can see.

Pretty sure it's not a beneficial insect. You can just rub them off with your fingers, you know...

Like carolb says, take a damp cloth and gently rub the leaves. If the "spots" come off - problem solved, cleanly and inexpensively and organically. I can't tell from the photo what is there- looks to me like possibly 3 separate issues.