I don't hide my pump. I put it where it's most convenient for me. It's usually on my belt/waistband and I like that as it's easy to access and I also use it as a clock : D
People don't notice it as much as I thought they would. If I bolus on it or something, they notice, but a number of people at work hadn't noticed it at all. Usually, if they do, they're interested in finding out more about it. I've never had anyone react negatively.
I don't use a case for my pump when it's on my belt. I just use the cool little clip that came with it. I think my pump is quite slim and non-medical looking, so it's quite discreet.
I honestly don't care about people seeing it. I love my pump and I'll continue to wear it as I choose.