You can change the Iterate mediator as below. Assign the values to the property and use it in the URL.

<iterate id="iterate-over-users" preservePayload="true" attachPath="json-eval($.users)" expression="json-eval($.users)">
<target>
<sequence>
<property name="uri.var.name" expression="json-eval($.users.name)"/>
<property name="uri.var.id" expression="json-eval($.users.id)"/>
<send>
<endpoint>
<http method="POST" uri-template="http://www.mocky.io/v2/5185415ba171ea3a00704eed/{uri.var.name}/{uri.var.id}"/>
</endpoint>
</send>
</sequence>
</target>
</iterate>