Why do my Box2D bodies occasionally get stuck and separate forcibly?

I’m making a space game with LibGDX and Box2D. I made a video here to illustrate the issue.

Verbal description: When objects collide, they sometimes get stuck together and are then suddenly separated by a strong force.

Both objects have identical body definitions and fixtures:

bod = new BodyDef();
bod.type       = type;
bod.allowSleep = false;

shape = new CircleShape();
shape.setRadius(values[0]);

fix = new FixtureDef();
fix.restitution = 0f;
fix.friction    = 1f;
fix.shape       = shape;
fix.density     = 1f;

worldBod = world.createBody(bod);
worldBod.setTransform(position.x, position.y, 0);
worldBod.createFixture(fix);

Why might this be happening? How can I fix it?

Update: Here is some more info.

The Player class contains a function update(float deltaTime) with the rest listed below

force.x += (directionVector.x * SPEED)*deltaTime;
force.y += (directionVector.y * SPEED)*deltaTime;


//This helps keep the object in control from preventing forces greater then 3
if(force.x >= 3){
    force.x = 3;
}if(force.x <= -3){
    force.x = -3;
}if(force.y >= 3){
    force.y = 3;
}if(force.y <= -3){
    force.y = -3;
}
//This quickly reduces the force back down to 0
force.x *= 0.5;
force.y *= 0.5;

this.getBody().applyForceToCenter(force, true); 

In the render part of the main game class I step the world with

gameWorld.step(Gdx.graphics.getDeltaTime(), 6, 6);
//although increasing or decreasing the itterations seems not to help

and Finally the hexagon’s are created using the ShapeRenderer pulling the position and

sr.setProjectionMatrix(camera.combined);
sr.begin(ShapeType.Line);
sr.circle(p1.getBody().getPosition().x, p1.getBody().getPosition().y, 1);
sr.circle(barrierPole.getBody().getPosition().x, barrierPole.getBody().getPosition().y, 1);
sr.end();