What happens if I don't use a relay for 5V pump I am trying to build an automatic watering system by following some examples. However, I don't have all the components for the entire system, therefore I have built it in Fritzing using only the components that I have (see scheme below):



I didn't build the physical version yet, because I am not sure that such a system would work without burning anything. In many examples, people connect the pump to a Relay Module, but since I don't have it yet, I would like to build it like this until I set up the watering system.

Can anyone help me understand why a relay would make it better or worse? 

P.S. I have a JPC-3F relay, but I can see that the Relay Module contains multiple components. Is it possible to add the JPC relay to the pump without having the entire Relay Module? Would I need extra components for that?

Thank you!

EDIT: Thanks to the answer from ratchet freak, I have added resistances and a transistor. It works fine, but the same question stands. Do I still need a relay in this case?
You should put a resistor in series with the led to limit the current.

The IO pins cannot source enough current to run the pump without damaging themselves. That's why you need a buffer of some kind.

The extra components in the relay module are a transistor to do the actual switching and a reverse-biased flyback schottky diode in parallel with the relay coil. The flyback diode is required to absorb the voltage spike generated by the coil getting switched off and acting like an inductor. 

You can use a transistor to switch the motor directly assuming you can find one that can handle the current draw. If you do then you absolutely will need a flyback diode on the motor to avoid damage to the transistor.