IAM user limit is 5000 per AWS account. I have more users than this.
Please tell me if there is any way to have more than 5000 IAM users.
I am quite not sure or convinced that you have a need for more than 5000 AWS IAM Users; the direct implication is that there are 5000+ people or applications who are operating under a single AWS account.
Be sure your application's users aren't the same as your IAM users; example assume you are running a simple Blog / CMS -> which has user roles of admin, content creator, content publisher, content editor; under each roles you have 10 different users so there would be 40 users [ 4 Roles x 10 Users in each Role = 40 users ]. These users would be created under application / infra layers and not IAM users.
The default maximum limit is 5000 users per AWS account. Beyond which you need to workout a solution with STS - http://docs.aws.amazon.com/STS/latest/UsingSTS/Welcome.html.
Again if you need 5000+ IAM users per AWS account; the simplest way is to separate out AWS accounts for individual application [ or also use sub accounts ]