I agree with the sentiments above in regards to picking project teams. Overall it is important to take a look not only at the team from a technical standpoint but from an interpersonal standpoint as well. If a team cannot seem to mesh well in terms of their personalities, it is rather difficult to progress a project to its end goal.
If there is an issue with the internal team it could severely hinder the project and the solution may not always be as simple as replacing the individuals that are causing tension. Clearly when picking out a project team you aim to ensure that situations like that do not occur but there still is the possibility of that happening. What are some possible ways a project manager can ease tension that in a group?