Customers are the most important part of any firm. Looking after the customer is a given - or at least should be! It is a relationship that needs work and attention. Remember that any asset - in this case the relationship - deteriorates if left neglected. Assets need attention and care.
So this makes complete sense for external customers but it just as true for internal customers. Customers to your work are just as sacred and should be dealt with, with the same care and attention. Ask them what they want, educate them about what you can do, deal with queries promptly, treat with respect....you wouldn't shout at an external customer so why an internal?
People who build strong internal networks will always be valuable. People who see the internal customer as sacred will be valued. People will want to nurture that relationship not look for other alternatives e.g. outsourcing. Remember the best way to protect your job is to do it brilliantly! If you do the job in isolation and not create added value then why would people not see this as a commodity that could be bought "cheaper". Add value...to add success...to add security.