The conjugation of the present tense of komen (to come) is perfectly regular, it is just the stem that is irregular:
Simple present:
| ik
| kom
| we
| komen
|
| je
| komt
| jullie
| komen
|
| hij
| komt
| ze
| komen
|
Simple past:
| ik
| kwam
| we
| kwamen
|
| je
| kwam
| jullie
| kwamen
|
| hij
| kwam
| ze
| kwamen
|
Past participle: gekomen
Can you see the irregularity?
Recall the first stem rule: a long vowel infinitive requires a long vowel stem. At least, this is what goes for regular verbs. In the case of the long-vowel-verb komen, we would expect the stem to be koom. But instead, we have a short-vowel-stem kom.
A few examples of verbs with the same conjugation as 'komen': 'bekomen' (to recover), 'ontkomen' (to escape), 'overkomen' (to happen to), 'aankomen' (to arrive, to put on weight).
Note that the examples above give you the unstressed personal pronouns. Some pronouns change when they are stressed in a phrase: je/jij, we/wij, ze/zij (both singular and plural).
Questions? 
