How can you make your team members work as a team although they have got different characters and there is an argument between some of them?

One of the important factor is alignment of strategy of particular team with department and organizations strategy.It's responsibility of management, department head to insure that all team members are working towards the organization goals and people hired in department which are culturally fit.Once all above taken care such kind of situations are unlikely to occur.

by determine their roles and avoiding eddy current negotiations between them

1) Understand the aggressive sales team members to divide to2 groups to achieve goals. 

2) Group Discussion and work shops to know where each one stands

3) Personal meeting with each one  to understand the actual root cause

4) Psychological approach individually by relating personal life 

4) Proper  orientation  towards goal

 

In my opinion group activities should be done on regular basis.
We had organized a very unique workshop to bring the team together.25 simple questions were given to the team members and were to answer in60 minutes.
The challenge was who ever finishes first will help other to writes the answer.
The competition was titled " Helping Hand Gets a Band" every team member were distributed10 bands to give if they needed help, who ever collects maximum bands will be the team leader.
The quality of answers were to be also evaluated by a Management Consultant but the company objective was to bring in cohesiveness between team members.
Short adventure trips like hiking also develops team spirit.
There are many such methods which helps team mates to develop friendship particularly when they are from multi cultural backgrounds .
Hope you find my experience useful.