Sparring is great fun, but also seems to be a great source of anxiety, at least until you get into it. The chances of sustaining any sort of injury from it is extremely low, because the pace is set by mutual feedback. As a rule, higher rank/more experienced fighter sets the pace, at a level appropriate for their partner. Nobody wants to beat up on noobs, and if they consistently do, they in turn will get beaten up on, and likely quit. Bullies dont tend to stick around too long because their egos cant take it.
This is how my coach handled it. He rarely broke up sparring rounds, but if you clearly beat up on someone he would pair you with someone clearly better than you next time and let them beat up on you. Eventually everyone sees that the best way to train is to go with the flow, focus on technique, and not paint a target on yourself.
Sparring with people clearly lower level than you doesn't help you improve much, though it's a chance to experiment a little more. The best fun and most productive sparring rounds were always with people about equal or a little bit higher skill level.